Fresh Properties and Test Methods. ▫ Flowability. ▫ Flow table test for mortar. ▫
Modified slump test for concrete. ▫ Compactability. ▫ Compaction factor test.
Design, Testing, Production and Construction of SemiFlowable Self-Consolidating Concrete for Slip-Form Paving Gilson Lomboya, aCivil
Kejin Wanga,
Peter Taylorb,
Surendra P. Shahc
Construction and Environmental Engineering, Iowa State University bNational Concrete Pavement Technology Center, Institute of Transportation cCenter for Advanced Cement-Based Materials, Northwestern University
Introduction
Collaboration
National Concrete Pavement Technology Center (CP Tech), ISU
Department of Civil Construction and Environmental Engineering (CCEE), ISU
Center for Advanced Cement-Based Materials (ACBM), NU
Three Phases (2004-2011)
feasibility study
mixture development
field applications 2
Basic Properties of SFSCC
Semi-Flowable Self-Consolidating Concrete (SFSCC) Shape Stability
Conventional Slip-form
SelfConsolidation
Semi-Flowable and Self-Consolidating
Conventional Self-Consolidating
Extruded slab using a mini-paver Slip-form without consolidation 3
Fresh Properties and Test Methods
Flowability
Flow table test for mortar
Modified slump test for concrete
Compactability
Compaction factor test
Shape holding ability
Slip-Form Paving Performance
4
Flowability: Flow Table Test
AASHTO M152 (ASTM C230)
Initial flow 10%
Flow at 18 drops 138% (9.5±0.2in)
5
Flowability: Modified slump test
ASTM C1611 method A
Unrodded
Slump – 6-8 in
Spread – 11-13 in
Symmetric cone shape
SFSCC slump and flow
6
Compactability: Compaction Factor
Ratio of the unit weight of unrodded concrete to the unit weight of rodded concrete
Consolidation by AASHTO T126 (ASTM C192) or AASHTO T23 (ASTM C31)
Good self-consolidating concrete shall have a compaction factor close to or equal to 1
7
Compactability: Shape Holding Ability
Green stength test – amount of compressive load a molded fresh concrete can carry until collapse, 0.2-0.4 psi
Method A SFSCC
dry sand
slump cone
mold base
SFSCC
SFSCC
Step2: SFSCC cylinder after removing mold
Step3: Loading SFSCC with dry sand
2.4 5 in
collar
4 in ø
lightweight container
Step1: Setup for molding unrodded SFSCC cylinder
8
Compactability: Shape Holding Ability Method B
4 in ø
8 in
Step1: Loosely filled mold with SFSCC dropped 15 times
SFSCC
Step2: SFSCC with mold removed
Step3: Loading SFSCC with dry sand 9
Slip-Form Paving Performance
Mini-paver test Slip form Platform for concrete
Slip form movement direction
Vertica l leg (concre te in)
Fresh concrete Standing concrete provides consolidation pressure
Weight chamber
Base
Drag cables
Front of mini-paver
g al le zont out) i r o H crete (con
Rear of mini-paver
Cross section of mini-paver
Six inch SFSCC slab cast with mini-paver
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SFSCC Mixture Proportioning
Cementitious Materials
Type I cement – AASHTO M85 (ASTM C150)
Supplementary cementitious materials – AASHTO M295 (ASTM C618) and ASTM C989
Aggregates – AASHTO M6, AASHTO M80 (ASTM C33)
Admixtures
air entraining agents, water reducing agents, viscosity modifying agents, and shrinkage reducing admixtures, thixotropes
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Design of Mortar (sand volume≈50%) (admixtures)
Selection of Coarse Aggregates (Gradation meets ASTM, Volume≈30% of concrete)
Not Good
SFSCC Mixture Proportioning
Mini-Paver test
Flow Table test
Non-rodding Slump and Compaction tests
Not Good
Good Hardened Properties Good Fo≈10% NO F16 to 18≈9.5±0.2 in YES
NO
S≈6-8%, D≈12", Cone Shaped, CF>0.95
YES
SF-SCC
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SFSCC Mixture Proportioning Table 1. Samples of mixture proportions of SFSCC Cement Fly Ash No (pcy) (pcy)
Slag (pcy)
Water (pcy)
F.A. (pcy)
C.A. (pcy)
AEA HRWR RMA (oz/cy) (oz/cy) (oz/cy)
Thixotrope (pcy)
Fiber (pcy)
1
594
249
295
1306
1372
6.3
2
559
243
310
1225
1448
6.0
3
540
231
293
1204
1542
5.8
4
504
218
250
1340
1562
5.4
14.8
43.0
2
5
432
144
250
1340
1562
5.4
21.0
34.6
2
144
2 4
Table 2. Properties of sample SFSCC No 1 2 3 4 5
Slump (in)
Spread (in)
7.00 6.00 7.50 6.75 7.00
12.5 11.0 12.5 12.0 13.0
Compaction Compressive Strength (psi) Factor % 28 days 56 days 98 6377 6754 99 6739 6957 99 6536 7288 98 4667 5652 99 5551 5913 13
Production and Construction
Concrete Production
Batching - accurate, consistent and reliable
mixing and delivery shall comply with AASHTO M157 (ASTM C94)
Slump, Spread and Shape of the concrete are measured with the modified slump test
Air content of the concrete is also measured according to AASHTO T152 (ASTM C231 method B)
When a scale is available on site, the compaction factor can also be determined
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Production and Construction
Paving Equipment
SFSCC involves placement of concrete on grade in the front of the paver and extrusion of the concrete. After SFSCC is placed on grade in front of the paver
It shall be uniformly spread along the width of the form and shall have a minimum height of 12 in above the thickness of the resulting slab.
Concrete that goes through the paver shall be at least 2.5 minutes in the form before it exits to be able to gain sufficient green strength.
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Production and Construction
Paving Equipment
Paver used for SFSCC field trial
Bike Path constructed from SFSCC
16
Production and Construction
Finishing, Texturing, Jointing
Minimal hand finishing may be applied using bull floats
Texturing and jointing can be done using the same methods as those for conventional slip-form concrete pavement
Curing and Maintenance
All curing methods for conventional concrete pavements can be applied to SFSCC.
Because the hardened SFSCC has been shown to have similar mechanical properties as conventional pavement concrete, the maintenance would also be expected to be the same. 17
Hardened Properties and Testing
The performance of SFSCC shall be similar to that of conventional pavement concrete.
The common tests for the concrete are
Compressive strength (AASHTO T22 / ASTM C39),
Freeze-Thaw durability (AASHTO T161 / ASTM C666A),
Rapid chloride ion permeability (AASHTO T277 / ASTM C1202),
Porosity (ASTM C642)
Scaling resistance to deicing chemicals (ASTM C672).
18
Conclusions
SFSCC mixture design can be developed based on a performance-based mixture design method. The design method is divided in mortar design, selection of aggregates, mini-paver test and hardened property testing.
SFSCC can successfully be prepared in a commercial batching plant as in the lab. Upon delivery of the concrete to the paving site, it shall be tested with the modified slump test.
The paving equipment shall distributed concrete uniformly in front of the form for proper consolidation and the horizontal form shall be sufficiently long for the concrete to follow and attain green strength to hold its shape.
SFSCC requires minimal finishing. Texturing, jointing, and curing of SFSCC pavements can be done using the same methods as those for conventional slip-form concrete pavement.
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The End
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Design of Mortar • w/b à ACI 211.1 à ACI 318R • Initial fine aggregate volume≈50% • Admixtures
Selection of Coarse Aggregates • Gradation meets à AASHTO M80 • Volume≈30% of concrete
Mini-Paver test
Not Good
SFSCC Mixture Proportioning
NO
Fo≈10% F16 to 18≈138±5 mm
• Non-rodding Slump à ASTM C1611(A) • Compaction tests à AASHTO T126 à AASHTO T23
Hardened Properties • Strength à AASHTO T22 • F-T durability à AASHTO T161 • RCP à AASHTO T277 • Porosity à ASTM C642 • Scaling resistance à ASTM C672
Good Slump≈175±25 mm, Spread≈300±25 mm,
YES
Not Good
• Flow Table test à AASHTO M152
Adjust coarse aggregate content
Adjust fine aggregate and admixture content
Good
NO
Cone Shaped, Comp.Fac.≥98%
SF-SCC YES 21
